Views: 0 Author: Site Editor Publish Time: 2025-08-12 Origin: Site
Polyester-based thermoplastic polyurethane (TPU) has become a widely favored material in many industries due to its unique blend of high elasticity, abrasion resistance, and clarity. It combines the strength and flexibility needed for durable consumer and industrial products such as footwear, films, hoses, cable sheaths, and industrial belts. However, despite its outstanding properties, polyester TPU faces a significant challenge: its susceptibility to hydrolysis. This chemical degradation caused by moisture can compromise the material’s performance, especially in humid, wet, or outdoor environments. Fortunately, advancements in stabilizer technology, particularly the use of light yellow liquid hydrolysis stabilizers, have offered an effective way to protect polyester TPU from premature degradation. These stabilizers not only enhance longevity but also maintain the material’s mechanical and optical properties, making them a smart choice for manufacturers looking to future-proof their TPU products.
Polyester-based TPU is a class of thermoplastic elastomers made by reacting polyester polyols with diisocyanates and chain extenders. This results in a material that combines the toughness and elasticity of rubber with the processing versatility of thermoplastics.
One of the standout features of polyester TPU is its high elasticity, allowing it to stretch and recover its shape without damage. It also boasts excellent abrasion resistance, making it ideal for applications involving wear and tear. Additionally, many polyester TPUs are naturally transparent or translucent, providing aesthetic advantages in applications like films or clear coatings.
Thanks to these properties, polyester TPU is commonly found in:
Footwear: Especially in midsoles, outsoles, and performance shoe components.
Films: Flexible packaging and protective films benefit from TPU’s toughness and clarity.
Hoses and cable sheaths: TPU’s flexibility and durability help protect internal wiring and fluids.
Industrial belts: Belts in manufacturing and conveyor systems use TPU for abrasion resistance and elasticity.
Despite its strengths, polyester TPU contains ester bonds in its backbone, which makes it vulnerable to hydrolysis — a chemical reaction with water that gradually breaks down these bonds. This susceptibility limits the material’s lifespan in moisture-rich environments unless adequately stabilized.
Hydrolysis in polyester TPU happens when moisture penetrates the polymer and reacts with the ester groups in its molecular chains. This reaction cleaves the bonds, causing the polymer chains to shorten and lose integrity — a process known as chain scission.
As hydrolysis progresses, the TPU’s physical properties deteriorate noticeably:
Loss of tensile strength: The material becomes weaker and less able to withstand stretching forces.
Brittleness: Instead of flexible and elastic behavior, the TPU becomes stiff and prone to cracking.
Cracking: Surface and internal cracks develop, accelerating mechanical failure.
Hydrolysis is especially problematic in tropical regions where heat and humidity are high. Outdoor applications exposed to rain or water splashes also suffer, as do components used in wet processing or water-contact scenarios.
Anti-hydrolysis agents, also called hydrolysis stabilizers, are additives that protect polymers by either reacting with or scavenging water and degradation products, preventing or slowing down the breakdown of ester bonds.
These stabilizers function by:
Reacting with carboxylic acid end groups formed when ester bonds break, effectively “capping” reactive sites.
Neutralizing moisture or catalyzing substances that accelerate hydrolysis.
Creating a barrier effect to slow water diffusion into the polymer matrix.
Unlike polyester TPUs, polyether-based TPUs are much more resistant to hydrolysis because their backbone contains ether rather than ester linkages. However, polyester TPUs generally provide better mechanical strength and abrasion resistance, making stabilization necessary for applications where hydrolysis could otherwise reduce lifespan.
Light yellow liquid hydrolysis stabilizers often consist of polycarbodiimide-based compounds or similar chemistries known for their effectiveness in protecting polyester polymers. These compounds chemically interact with hydrolysis byproducts and prevent further chain scission.
The liquid form provides several processing and performance advantages:
Easy dosing and incorporation: The liquid additive can be accurately measured and added directly into the TPU melt during extrusion or compounding without complex pre-dispersion.
Good dispersion: Liquids mix uniformly, reducing the risk of agglomerates that can cause defects.
Stable color: The light yellow tint is subtle and typically does not affect the final product’s clarity or color, important for transparent or light-colored TPUs.
The primary benefit of these stabilizers is their ability to extend TPU lifespan in humid and wet environments. Products maintain tensile strength and flexibility far longer than unstabilized versions when exposed to moisture.
Unlike some powder or high-viscosity alternatives, light yellow liquid stabilizers do not adversely affect:
The mechanical properties such as elasticity, hardness, or tensile strength.
The transparency or aesthetic qualities of clear TPU products.
TPU treated with these stabilizers retains its original flexibility and tensile strength even after extended aging in hot, humid conditions, reducing brittleness and cracking risks.
Compared to powders or solid anti-hydrolysis additives, the liquid form:
Eliminates the need for pre-dispersion or high-shear mixing.
Allows more consistent and uniform incorporation during standard manufacturing processes.
Light yellow liquid hydrolysis stabilizers are typically incorporated directly into the TPU melt during the extrusion or compounding process. This method allows for quick and uniform dispersion of the stabilizer throughout the polymer matrix, ensuring effective protection against hydrolysis without the need for additional processing steps such as pre-dispersion or high-shear mixing. Because the stabilizer is in liquid form, it blends easily with the TPU melt, facilitating a smooth manufacturing workflow and maintaining consistent product quality. This straightforward addition process also helps minimize production downtime and reduces handling complexity compared to solid or powder additives.
The optimal dosage of light yellow liquid hydrolysis stabilizer generally ranges between 0.5% and 2.0% by weight of the total TPU formulation. The exact amount depends on several factors:
Hydrolysis resistance requirements: Products intended for highly humid or wet environments, such as outdoor applications or tropical climates, may require higher dosages to ensure long-term durability.
TPU grade: Different polyester TPU grades have varying base susceptibility to hydrolysis, so the stabilizer dosage may be adjusted accordingly.
Application conditions: For less demanding indoor or dry environments, lower dosages can be sufficient to provide adequate protection.
Manufacturers should tailor stabilizer levels to balance cost and performance based on specific use cases.
Light yellow liquid hydrolysis stabilizers are designed to be compatible with standard polyester TPU formulations, ensuring they do not interfere with the polymerization process or the final material properties. They also work well with common TPU pigments and additives, avoiding unwanted color changes or processing difficulties. However, when formulating with unique fillers, specialty pigments, or other proprietary additives, manufacturers should conduct compatibility tests to verify that the stabilizer performs effectively without adverse interactions. This ensures optimal product appearance, stability, and hydrolysis resistance across diverse TPU applications.
Light yellow liquid hydrolysis stabilizers provide an effective and convenient solution to the common challenge of moisture-induced degradation in polyester TPU. By integrating these advanced additives, manufacturers can greatly enhance the durability of TPU products used in humid, wet, and outdoor environments—without sacrificing mechanical strength, flexibility, or transparency. Compared to traditional powder or high-viscosity stabilizers, the liquid form offers easier handling and more uniform dispersion during processing. For businesses involved in footwear, films, hoses, and other TPU applications, adopting light yellow liquid hydrolysis stabilizers is a strategic way to protect materials and ensure lasting performance. To learn more about high-quality hydrolysis stabilizers and find tailored solutions, we recommend reaching out to Suzhou Ke Sheng Tong New Materials Technology Co., Ltd. Their expertise can help you optimize your TPU formulations for superior durability and reliability.
